The present invention relates to a guiding catheter used in Percutaneous Transluminal Coronary Angioplasty procedures. More particularly, the present invention concerns a guiding catheter having an inflatable balloon disposed in its wall for securing a guide wire within the lumen of the guide catheter during replacement of a balloon catheter on the guide wire.
In Percutaneous Transluminal Coronary Angioplasty (PTCA) procedures, a balloon catheter is introduced into an artery for the purposes of enlarging a vessel or opening a clogged artery or stuck valve in the heart or elsewhere to restore normal blood flow. A peripheral introduction of a balloon tip catheter enlarges and dilates a narrowed arterial lumen by inflating the catheter tip.
During PTCA it may be necessary to remove a balloon catheter from the guide wire in the guide catheter. Three common situations occur in which a balloon catheter is exchanged. One is when the first balloon does not satisfactorily reduce the transtenotic gradient and a high degree of residual stenosis exists. The balloon catheter is usually removed and a larger balloon inserted to complete the dilation.
Another situation arises when the lesion is too tight to accommodate the balloon. Here the balloon needs to be removed and replaced with a smaller balloon catheter to partially dilate the lesion, and the larger balloon reinserted to complete the dilation. In the third case, the operator may wish to inject a large volume of contrast to achieve maximum visualization of the lesion. This is accomplished by pulling the balloon into the catheter body before injecting the contrast. The position of the guide wire must be maintained across the lesion so that the balloon catheter may be repositioned if needed.
To facilitate a catheter balloon exchange, it is common to use a guide wire that is twice as long as the steerable guide wire to pull the balloon dilation catheter back without removing the guide wire. Otherwise when a catheter wire is removed, replacement of the wire will require renegotiation of the anatomy with a new wire, increasing the risks of intimal dissection. Conventional devices employ an exchange-wire technique to achieve the extra length. A crimping tool is used to bond an extension wire to the catheter wire so that the balloon catheter can be exchanged without removing the wire. However, users frequently encounter problems when sliding the catheter balloon over the crimped portion of the wire.
Other devices employ an extra guide wire during the entire procedure. In both techniques the process is cumbersome, requiring several additional steps, increasing fluoroscopy time, and increasing the risk of losing the position of the guide wire. Another device, called a trapper, incorporates a balloon that is separately inserted into the guiding catheter to trap the guide wire against the catheter wall. Use of the trapper device is cumbersome because it is separate from the catheter, involves additional hardware and requires an involved procedure.
Further details of the devices used in angioplasty procedures can be found in U.S. Pat. No. 4,932,959 (Horzewski), U.S. Pat. No. 5,054,500 (Littleford) and U.S. Pat. No. 5,059,178 (Ya). U.S. Pat. No. 4,932,959 (Horzewski) discloses a dilation catheter with a releasably secured guide wire. The apparatus discloses inner and outer tubular members that are concentrically disposed. The inner tubular member incorporates a flexible portion therein. An annular passageway is defined between the two tubular members, which contains inflation fluids. When inflation fluid is directed into the annular passageway, the flexible portion of the inner tubular member expands inwardly to grip the guide wire disposed within the inner lumen thereof to improve the pushability of the moveable catheter assembly.
U.S. Pat. No. 5,054,500 (Littleford) relates to an apparatus and method for guiding and positioning a catheter. The apparatus incorporates an inflatable outer collar at the distal end of the catheter body for controlling the position of the catheter, which may be inflated to press against the passageway to hold the guide catheter in place during operation.
U.S. Pat. No. 5,059,178 (Ya) discloses a method of isolating a thrombus in the blood vessel of a patient. The catheter apparatus discloses a first and second inflatable balloon. The first balloon is positioned downstream of the thrombus, and the second balloon is positioned upstream of the thrombus. The purpose of the balloons is to isolate the thrombus so that a thrombus dissolving agent may be applied in isolation from the rest of the body. Once the thrombus is dissolved, it is removed through a suction catheter. A third balloon is disclosed, which is used to expand the stricter after the thrombus is removed.
None of the foregoing patents disclose a satisfactory means for retaining a guide wire in position during the exchange of balloon catheters. A need exists for a more efficient apparatus and method for exchanging balloon catheters without the risks and complicated procedures associated with the prior art.